Physical and chemical properties of trans-free fats produced by chemical interesterification of vegetable oil blends

Fat blends, formulated by mixing a highly saturated fat (palm stearin or fully hydrogenated soybean oil) with a native vegetable oil (soybean oil) in different ratios from 10:90 to 75:25 (wt%), were subjected to chemical interesterification reactions on laboratory scale (0.2% sodium methoxide catalyst, time=90 min, temperature=90°C). Starting and interesterified blends were investigated for triglyceride composition, solid fat content, free fatty acid content, and trans fatty acid (TFA) levels. Obtained values were compared to those of low- and high-trans commercial food fats. The interesterified blends with 30–50% of hard stock had plasticity curves in the range of commercial shortenings and stick-type margarines, while interesterified blends with 20% hard stock were suitable for use in soft tubtype margarines. Confectionery fat basestocks could be prepared from interesterified fat blends with 40% palm stearin or 25% fully hydrogenated soybean oil. TFA levels of interesterified blends were low (0.1%) compared to 1.3–12.1% in commercial food fats. Presented at the 88th AOCS Annual Meeting and Expo, May 11–14, 1997, Seattle, Washington.     

Trans‐free fats through interesterification of canola oil/palm olein or fully hydrogenated soybean oil blends

Binary blends of canola oil (CO) and palm olein (POo) or fully hydrogenated soybean oil (FHSBO) were interesterified using commercial lipase, Lypozyme TL IM, or sodium methoxide. Free fatty acids (FFA) and soap content increased and peroxide value (PV) decreased after enzymatic or chemical interesterification. No difference was observed between the PV of enzymatically and chemically interesterified blends. Enzymatically interesterified fats contained higher FFA and lower soap content than chemically prepared fats. Slip melting point (SMP) and solid‐fat content (SFC) of CO and POo blends increased, whereas those of CO and FHSBO blends decreased after chemical or enzymatic interesterification. Enzymatically interesterified CO and POo blends had lower SMP and SFC (at some temperatures) than chemically interesterified blends. The status was reverse when comparing chemically and enzymatically interesterified CO and FHSBO blends. The induction period for oxidation at 120°C of blends decreased after interesterification. However, chemically interesterified blends were more oxidatively stable than enzymatically interesterified blends. Interesterified blends of CO and POo or FHSBO displayed characteristics suited to application as trans‐free soft tub, stick, roll‐in and baker's margarine, cake shortening and vanaspati fat.     

Chemical and enzymatic interesterification of a beef tallow and rapeseed oil equal‐weight blend

A mixture of beef tallow and rapeseed oil (1:1, wt/wt) was interesterified using sodium methoxide or immobilized lipases from Rhizomucor miehei (Lipozyme IM) and Candida antarctica (Novozym 435) as catalysts. Chemical interesterifications were carried out at 60 and 90 °C for 0.5 and 1.5 h using 0.4, 0.6 and 1.0 wt‐% CH₃ONa. Enzymatic interesterifications were carried out at 60 °C for 8 h with Lipozyme IM or at 80 °C for 4 h with Novozym 435. The biocatalyst doses were kept constant (8 wt‐%), but the water content was varied from 2 to 10 wt‐%. The starting mixture and the interesterified products were separated by column chromatography into a pure triacylglycerol fraction and a nontriacylglycerol fraction, which contained free fatty acids, mono‐, and diacylglycerols. It was found that the concentration of free fatty acids and partial acylglycerols increased after interesterification. The slip melting points and solid fat contents of the triacylglycerol fractions isolated from interesterified fats were lower compared with the nonesterified blends. The sn‐2 and sn‐1,3 distribution of fatty acids in the TAG fractions before and after interesterification were determined. These distributions were random after chemical interesterification and near random when Novozym 435 was used. When Lipozyme IM was used, the fatty acid composition at the sn‐2 position remained practically unchanged, compared with the starting blend. The interesterified fats and isolated triacylglycerols had reduced oxidative stabilities, as assessed by Rancimat induction times. Addition of 0.02% BHA and BHT to the interesterified fats improved their stabilities.     

Trans-free margarine from highly saturated soybean oil

Highly saturated (HS) soybean oil (SBO), which contained 23.3% palmitic acid (C_16:0) and 20.0% stearic acid (C_18:0), was interesterified at 70°C in preparation for the processing of a trans-free margarine. High-performance liquid chromatography analysis of the triacylglycerides and analysis of the sn-2 fatty acid composition showed no further change after 10 min of interesterification. The interesterified HS SBO had a slip melting point of 34.5°C, compared with 9.5°C in the non-interesterified HS SBO, and increased melting and crystallization temperatures were found using differential scanning calorimetry. Analysis of solid-fat content by nuclear magnetic resonance revealed the presence of only a small amount of solids above 33°C. A 50:50 blend of interesterified HS SBO and SBO with a typical fatty acid composition was used to make the margarine. Compared to commercial soft-tub margarine, the maximal peak force on the texture analyzer of this blended margarine was about 2.3 times greater, the hardness about 2.6 times greater, and adhesiveness about 1.5 times greater. There were small but statistically significant differences (α=0.05) in the sensory properties of spreadability, graininess, and waxiness between the commercial and blended margarines at 4.5°C and, except for graininess, at 11.5°C. These very small differences suggest a potential use for HS SBO in margarine products.     

Margarine and shortening oils by interesterification of liquid and trisaturated triglycerides

Liquid vegetable oils (VO), including cottonseed, peanut, soybean, corn, and canola, were randomly interesterified with completely hydrogenated soybean or cottonseed hardstocks (vegetable oil trisaturate; VOTS) in ratios of four parts VO and one part VOTS. Analysis of the reaction products by high-performance liquid chromatography showed that at 70°C and vigorous agitation, with 0.5% sodium methoxide catalyst, the reactions were complete after 15 min. Solid-fat index (SFI) measurements made at 50, 70, 80, 92, and 104°F, along with drop melting points, indicated that the interesterified fats possess plasticity curves in the range of commercial soft tub margarine oils prepared by blending hydrogenated stocks. Shortening basestocks were prepared by randomly interesterifying palm or soybean oil with VOTS in ratios of 1:1 or 3:1 or 4:1, respectively. Blending of the interesterified basestocks with additional liquid VO yielded products having SFI curves very similar to commercial all purpose-type shortening oils made by blending hydrogenated stocks. Other studies show that fluid-type shortening oils can be prepared through blending of interesterified basestocks with liquid VO. X-ray diffraction studies showed that the desirable β′ crystal structure is achieved through interesterification and blending. Presented at AOCS Annual Meeting & Expo, Atlanta, Georgia, May 8–12, 1994.     

Reduction of Graininess Formation in Beef Tallow-Based Plastic Fats by Chemical Interesterification of Beef Tallow and Canola Oil

To manufacture beef tallow (BT)-based shortening and margarine with a reduced tendency to developing sandiness, BT/canola oil (CaO) blend (80:20 w/w), selected from the BT and CaO blends mixed in different ratios from 60:40 to 85:15 with 5% increments, was subjected to chemical interesterification (CIE) with sodium methoxide as the catalyst. The interesterified products were compared with the starting mixture in terms of solid fat content (SFC), and contents of high-melting point 1,3-disaturated long-chain fatty acid 2-monounsaturated long-chain fatty acid triacylglycerols (SUS TAGs) including 1,3-distearoyl-2-oleoyl-glycerol (StOSt), 1,3-dipalmitoy-2-oleoyl-glycerol (POP), and 1-palmitoyl-2-oleoyl-3-stearoyl-glycerol (POSt). Under the selected conditions: 60 °C, 0.6% CH₃ONa, 90 min, the CIE product had a SFC profile that meets suggested bakery fat requirements, besides a content of SUS TAGs which is 22.14% lower than that of the non-interesterified blend. Also the fat produced had stable β′ polymorphs, crystal morphology, crystal sizes (<20 μm), and could resist temperature fluctuations. The CIE product obtained herein has an increased potential for manufacturing bakery shortenings and margarines with reduced graininess formation, increasing the possibilities for the commercial use of BT and CaO.     

Electrochemical hydrogenation of edible oils in a solid polymer electrolyte reactor. Sensory and compositional characteristics of low Trans soybean oils

Soybean oils were hydrogenated either electrochemically with Pd at 50 or 60°C to iodine values (IV) of 104 and 90 or commercially with Ni to iodine values of 94 and 68. To determine the composition and sensory characteristics, oils were evaluated for triacylglycerol (TAG) structure, stereospecific analysis, fatty acids, solid fat index, and odor attributes in room odor tests. Trans fatty acid contents were 17 and 43.5% for the commercially hydrogenated oils and 9.8% for both electrochemically hydrogenated products. Compositional analysis of the oils showed higher levels of stearic and linoleic acids in the electrochemically hydrogenated oils and higher oleic acid levels in the chemically hydrogenated products. TAG analysis confirmed these findings. Monoenes were the predominant species in the commercial oils, whereas dienes and saturates were predominant components of the electrochemically processed samples. Free fatty acid values and peroxide values were low in electrochemically hydrogenated oils, indicating no problems from hydrolysis or oxidation during hydrogenation. The solid fat index profile of a 15∶85 blend of electrochemically hydrogenated soybean oil (IV=90) with a liquid soybean oil was equivalent to that of a commercial stick margarine. In room odor evaluations of oils heated at frying temperature (190°C), chemically hydrogenated soybean oils showed strong intensities of an undesirable characteristic hydrogenation aroma (waxy, sweet, flowery, fruity, and/or crayon-like odors). However, the electrochemically hydrogenated samples showed only weak intensities of this odor, indicating that the hydrogenation aroma/flavor would be much less detectable in foods fried in the electrochemically hydrogenated soybean oils than in chemically hydrogenated soybean oils. Electrochemical hydrogenation produced deodorized oils with lower levels of trans fatty acids, compositions suitable for margarines, and lower intensity levels of off-odors, including hydrogenation aroma, when heated to 190°C than did commercially hydrogenated oil.     

D. K. Bhattacharyya,Modification of tallow fractions in the preparation of edible fat products

Investigation has been carried out with an intention to prepare shortening, margarine fat bases, and value-added edible fat products like cocobutter substitute from tallow. For this, tallow was fractionated at low (12 and 15 °C) and intermediate (25 °C) temperatures by solvent (acetone) fractionation process. The stearin fractions (yield: 23—40% (w/w) and slip melting point: 45—50.5 °C) thus obtained were blended and interesterified with liquid oils, such as sunflower, soybean, rice bran etc. by microbial lipase catalyzed route. The olein fractions (yield: 60—77% (w/w) and slip melting point: 21—32.5 °C) were also chemically interesterified (using NaOMe) and biochemically (using Rhizomucor miehei lipase, Lipozyme IM 20). The olein fractions were also blended with sal (Shorea robusta) fat, sal olein, and acidolysed karanja (Pongamia glabra) stearin. As revealed from their slip melting point and solid fat index, the products thus prepared were found to be suitable for shortening, margarine fat bases, and vanaspati substitute.     

“Zerotrans” margarines: Preparation,structure, and properties of interesterified soybean oil-Soy trisaturate blends

The sodium methoxide-catalyzed random interesterification of liquid soybean oil-soy trisaturate blends was explored as a possible route to zerotrans margarine oils. Lipase hydrolysis of the rearranged fats showed that with 0.2% catalyst, interesterification is complete within 30 min at 75-80 C. The glyceride structures of natural and randomized soybean oil-soy trisaturate blends are presented, and relationships between their structure and physical properties are discussed. Organoleptic evaluations showed that randomization of the glyceride structure had no adverse effects on flavor and oxidative stability. Flavor evaluations made against a commercially hardened tub margarine oil showed that interesterified oil had comparable initial and aged flavor scores. X-ray diffraction studies demonstrated that randomized soybean oil-soy trisaturate blends possess the beta-prime crystal structure desirable for use in margarine production. Dilatometric data indicate that random interesterification of 20% by weight of soy trisaturate into the glyceride structure of soybean oil provides a product having a solid fat index suitable for use in a soft tub margarine. Presented at the AOCS Meeting, Chicago, September 1976.     

Modifications of butter stearin by blending and interesterification for better utilization in edible fat products

This work primarily aims to further modify the stearin fractions, obtained from anhydrous milk fat, after fractionation by dry process and by solvent process using isopropanol, for extending their scope of utilization in edible fat products. Butter stearin fractions, on blending with liquid oils like sunflower oil and soybean oil in different proportions, offer nutritionally important fat products with enriched content of essential fatty acids like C_18∶2 and C_18∶3. The butter stearin fraction from isopropanol fractionation, when interesterified with individual liquid oils by Mucor miehei lipase as a catalyst, yields fat products having desirable properties in making melange spread fat products with reasonable content of polyunsaturated fatty acids and almost zero trans fatty acid content.     

Analysis oftrans-18:1 isomer content and profile in edible refined beef tallow

Thetrans 18:1 acid content and profile for several samples of edible refined beef tallow were determined monthly over a period of one year. For this purpose, gas-liquid chromatography was combined with silver-ion thin-layer chromatography. The mean content oftrans-18:1 isomers was 4.9±0.9% (n=10) of total fatty acids with a minimum of 3.4% and a maximum of 6.2%. The distribution profile of individual isomers was also established. As in other ruminant fats (milk fat, meat fat), the main isomer is vaccenic (trans-11 18:1) acid. Other isomers, with their ethylenic bonds between positions 6 and 16, were found in lesser amounts. However, some slight but definite differences exist between beef tallow and cow milk fat. The relative proportion of vaccenic acid is higher in the former than in the latter. However, the distribution pattern oftrans-18:1 isomers in beef tallow closely resembles that in beef meat fat (lean part).     

Effect of PUFA at sn‐2 position in dietary triacylglycerols on the fatty acid composition of adipose tissues in non‐ruminant farm animals

The influence of the distribution of polyunsaturated fatty acids on the glycerol backbone of dietary triacylglycerols on the fatty acid profile of adipose tissue and muscle phospholipids was investigated in growing‐finishing pigs (48) and broiler chicken (84). The animals were fattened on barley/soybean meal diets supplemented with a blend of soybean oil and beef tallow, either in the ratio 3:1 w/w (high‐PUFA) or 1:3 w/w (low‐ PUFA). Part of the high‐ and low‐PUFA blends was chemically interesterified to randomly distribute all fatty acids over the three positions of the glycerol. Thus, two sets of diets of identical overall fatty acid composition, but differing in the distribution of fatty acids in the triacylglycerols, were fed. Growth performance and carcass composition were neither affected by fatty acid composition nor by randomisation of dietary fats in either animal species. Apparent digestibility of energy was slightly lower in pigs fed the low‐PUFA blends. Fatty acid profile of subcutaneous fat of pigs and broilers as well as of internal body fat (lamina subserosa) and muscle phospholipids of pigs varied according to the dietary fatty acid composition but was not affected by randomisation of dietary fats. These findings are explained in terms of the hydrolysis of TAG during transport of lipids from enterocytes to adipose tissue cells and the continuous lipolysis and re‐esterification of fatty acids that take place in adipose tissue cells.     

Low-<Emphasis Type="Italic">trans</Emphasis> Shortening and Spread Fats Produced by Electrochemical Hydrogenation

Partially hydrogenated soybean oils (90–110 IV) were prepared by electrochemical hydrogenation at a palladium/cobalt or palladium/iron cathode, moderate temperature (70–90 °C) and atmospheric pressure. The trans fatty acid (TFA) contents of 90–110 IV products ranged from 6.4 to13.8% and the amounts of stearic acid ranged from 8.8 to 15.4% (the higher stearic acid contents indicated that some reaction selectivity had been lost). The solid fat values and melting point data indicated that electrochemical hydrogenation provides a route to low-trans spreads and baking shortenings. Shortenings produced by conventional hydrogenation contain 12–25% trans fatty acids and up to 37% saturates, whereas shortening fats produced electrochemically had reduced TFA and saturate content. Electrochemical hydrogenation is also a promising route to low-trans spread and liquid margarine oils. Compared to commercial margarine/spread oils containing 8–12% TFA, the use of electrochemical hydrogenation results in about 4% TFA. Names are necessary to report factually an available data: the USDA neither guarantees nor warrants the standard of the product, and the use of the name USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Utilization of high-melting palm stearin in lipase-catalyzed interesterification with liquid oils

Palm stearin with a melting point (m.p.) of 49.8°C was fractionated from acetone to produce a low-melting palm stearin (m.p.=35°C) and a higher-melting palm stearin (HMPS, m.p.=58°C) fraction. HMPS was modified by interesterification with 60% (by weight) of individual liquid oils from sunflower, soybean, and rice bran by means of Mucor miehei lipase. The interesterified products were evaluated for m.p., solid fat content, and carbon number glyceride composition. When HMPS was interesterified individually with sunflower, soybean or rice bran at the 60% level, the m.p. of the interesterified products were 37.5, 38.9, and 39.6°C, respectively. The solid fat content of the interesterified products were 30–35 at 10°C, 17–19 at 20°C, and 6–10 at 30°C, respectively. The carbon number glyceride compositions also changed significantly. C₄₈ and C₅₄ glycerides decreased remarkably with a corresponding increase of the C₅₀ and C₅₂ glycerides. All these interesterified products were suitable for use as trans acid-free and polyunsaturated fatty acid-rich shortening and margarine fat bases.     

Physical and Sensory Attributes of a <Emphasis Type="Italic">trans</Emphasis>-Free Spread Formulated with a Blend Containing a Structured Lipid,Palm Mid-Fraction,and Cottonseed Oil

Physical and sensory attributes of an experimental trans-free margarine spread (MG-X) and two commercial margarine spreads (MG-A and MG-B) were studied. The trans-free margarine spread was formulated with a blend containing a structured lipid (SL) synthesized by reacting canola oil with 40% stearic acid (w/w), palm mid-fraction (PMF), and cottonseed oil (CTO). No trans fatty acids were detected in MG-X, whereas the trans fatty acid contents of MG-A and MG-B were 0.3 and 3.7% (w/w), respectively. MG-X was considerably firmer than MG-A and MG-B, less cohesive, and its adhesiveness was intermediate between those of MG-A and MG-B. MG-X’s stability to syneresis was also intermediate between those of MG-A and MG-B. Sensory evaluation showed that MG-X was comparable to MG-A in terms of spreadability and texture only, but was significantly different from MG-B in all attributes.     

Trans-18:1 acids in french tub margarines and shortenings: Recent trends

The fatty acid composition of twelve French tub margarines and three industrial shortenings was established with particular attention to theirtrans-18:1 acid content. Four of the twelve margarines (including two major brands, with 60% of market share) were devoid oftrans isomers, one contained less than 2%trans-18:1 acids, whereas the seven others had a mean content of 13.5 ± 3.6%trans isomers. Four years ago, no margarines with 0%trans-18:1 acids could be found. It is deduced that the recent Dutch and American studies on possible effects oftrans acids on human health (serum cholesterol, heart disease risks) may have had some influence on French margarine manufacturers. Presently, an average French tub margarine contains only 3.8% oftrans-18:1 acids instead of 13% four years ago. To protect brand names, some manufacturers have replaced partially hydrogenated oils with tropical fats or fully hydrogenated oils. On the other hand, two of the three shortenings had high levels oftrans-18:1 acids: 53.5 and 62.5%. This last value, obtained for a sample of hydrogenated arachis oil, seems to be one of the highest values ever reported for edible hydrogenated oils. In this sample,trans-18:1 plus saturated acids accounted for 85% of total fatty acids. This would indicate that shortening producers and users are not yet aware of recent dietary recommendations, probably because these products are not easily identifiable by consumers in food items, in contrast to margarines.     

Rapeseed oil in a two-component margarine base stock

A two-component margarine base stock with liquid oil as one component allowed for a lowertrans fatty acid content and at the same time provided for a higher essential fatty acid level than a one-component base stock. Transesterification softened a two-component margarine base stock and resulted in a steeper solid fat index curve, but did allow for a lowertrans fatty acid level in a margarine base stock. The high content of erucic acid in rapeseed oil did not change the physical properties of a margarine base stock and provided a good hardstock when this oil was hydrogenated. The use of a hydrogenated rapeseed oil ensured interchangeability of liquid oils in blends and rearranged blends, also seemed superior to soybean hardstocks in this respect.     

The development and application of novel vegetable oils tailor‐made for specific human dietary needs

Conventional edible oils, such as sunflower, safflower, soya bean, rapeseed (canola) oils, were modified to obtain high‐oleic, low‐linoleic or even low‐linolenic oils. The aim was to develop salad, cooking and frying oils, that are very stable against lipid peroxidation. They are also suitable for margarine blends, as additives to cheeses and sausages, or even as feed components. Oils containing higher amounts of medium‐chain length or long‐chain polyunsaturated fish oil fatty acids are suitable as special dietetic oils or as nutraceuticals. High‐stearic oils are designed as trans‐fatty acid‐free substitutes for hydrogenated oils. New tailor‐made (designer) oils are thus a new series of vegetable oils suitable for edible purposes, where conventional oils are not suitable.     

Detection of lard and randomized lard as adulterants in refined-bleached-deodorized palm oil by differential scanning calorimetry

A study was conducted to assess the use of differential scanning calorimetry (DSC) for detecting the presence of lard/randomized lard as adulterants in refined-bleached-deodorized (RBD) palm oil. Lard extracted from the adipose tissues of pig was chemically interesterified using sodium methoxide as catalyst. DSC thermal profiles of both genuine lard and randomized lard were compared with those of other common animal fats such as beef tallow, mutton tallow, and chicken fat. Lard and randomized lard were then blended with RBD palm oil in two series, in proportions ranging from 0.2 to 20%, and DSC analyses were obtained. The DSC cooling profiles of adulterated RBD palm oil samples showed an adulteration peak corresponding to lard/randomized lard in the low-temperature region. This peak was confirmed as an indicator of the presence of lard in RBD palm oil since similar experiments carried out using other common animal fats such as mutton tallow, beef tallow, and chicken fat showed that the lard adulteration peak could be distinctly identified. Using this method, a detection limit of 1% lard/randomized lard was reached (P<0.0001).     

Alteration of steryl ester content and positional distribution of fatty acids in triacylglycerols by chemical and enzymatic interesterification of plant oils

Steryl ester content of refined and interesterified corn, soybean, and rapeseed oils has been measured via clean-up on a short silica gel column, followed by high performance liquid chromatography with evaporative light-scattering mass detector. Chemical interesterification, catalyzed by sodium methoxide, led to random positional distribution of fatty acids in triacylglycerols and some increase in the steryl ester content of all three oils. Enzymatic interesterification, catalyzed by the immobilized lipase from Rhizomucor miehei (Lipozyme), resulted in a distinct reduction in steryl ester content, but essentially no alteration in positional distribution of fatty acids in triacylglycerols occurred. Formation of steryl esters during chemical and enzymatic interesterification was also examined by radioactive tracer technique with [4-¹⁴C]β-sitosterol added as marker to refined rapeseed oil and measurement of the radioactive steryl esters formed. Chemical interesterification of rapeseed oil resulted in moderate formation (10% of total radioactivity) of radioactive β-sitosteryl esters. Enzymatic interesterification of the oil, catalyzed by Lipozyme, led to little formation of radioactive β-sitosteryl esters, whereas with the lipase from Candida cylindracea high proportions (>90% of total radioactivity) of ¹⁴C-labeled β-sitosteryl esters were formed. Part of doctoral thesis of Roseli Ap. Ferrari to be submitted to Faculdade de Engenharia de Alimentos, Universidade de Campinas, Campinas, Brazil.